Employment of a ceramic based structure for the fabrication of certain components that require the chemical and mechanical properties of such construction is well recognized and non-limitedly exemplified in thin ceramic armor. One such structure that could be beneficial is a cured sandwich configuration comprising an upper length of ceramic-resin impregnated woven fiber and a lower length of ceramic-resin impregnated woven fiber in alignment with each other and having disposed therebetween discontinuous fibers optionally including filler material within a ceramic resin.
However, the present method of fabricating a combination of woven and discontinuous fibers unfortunately yields an inherently stressed end product that is not properly usable in many applications. The introduction of stress is caused by fabrication techniques which include laying a number of ceramic precursor resin-wetted woven fabric plies in a mold, adding a quantity of a mixture of discontinuous fibers, precursor resin, and, as desired, filler powders to the mold, and compressing the mold to form a green-state structure for subsequent ceramic conversion of the matrix by pyrolysis. Because the exposed surface of the fabric is uneven and erratic due to the weave at the bottom of the mold, the mixture containing the discontinuous fibers does not flow smoothly during compression of the mold, thereby resulting in both a nonuniform distribution of the mixture and a clumping of mixture at certain sites while causing degradation of mechanical properties of a finished part. Where clumping occurs, more pressure is placed on the woven fabric to thereby enhance non-uniformity of fiber volume and thickness of the woven section so affected. Second, and again due to non-uniformity of the mixture coupled with high molding pressures, a substantial number of internal stress points are introduced within the mixture in its green state. The stresses can cause warpage of the structure during pyrolytic curing and thereby substantially reduce utility of the structure for component fabrication.
In view of the above prior art construction methodology and resultant end product, it is apparent that a need is present for methodology and consequent end product wherein a continuous woven fiber and a discontinuous ceramic fiber can be coupled in a ceramic matrix to produce an end product having favorable properties for ceramic structural applications. Accordingly, a primary object of the present invention is to provide methodology for fabricating a precursor ceramic preimpregnated composite material comprising a continuous woven fiber and a discontinuous fiber combined with a ceramic precursor resin with or without filler powders for subsequent curing and non-stressed component construction.
Another object of the present invention is to provide methodology for fabricating, as well as an end product of, a woven-fiber and discontinuous-fiber ceramic matrix composite structure for subsequent component construction.
Yet another object of the present invention is to provide a cured woven-fiber and discontinuous-fiber ceramic matrix composite structure having uniform distribution of discontinuous fibers within a ceramic resin.
These and other objects of the present invention will become apparent throughout the description thereof which now follows.